Insertable cardiac monitors after cryptogenic stroke--a risk factor based approach to enhance the detection rate for paroxysmal atrial fibrillation.

BACKGROUND AND PURPOSE: Recently, the CRYSTAL AF trial detected paroxysmal atrial fibrillation (AF) in 12.4% of patients after cryptogenic ischaemic stroke (IS) or cryptogenic transient ischaemic attack (TIA) by an insertable cardiac monitor (ICM) within 1 year of monitoring. Our aim was (i) to assess if an AF risk factor based pre-selection of ICM candidates would enhance the rate of AF detection and (ii) to determine AF risk factors with significant predictive value for AF detection. METHODS: Seventy-five patients with cryptogenic IS/TIA were consecutively enrolled if at least one of the following AF risk factors was present: a CHA2DS2-VASc score ≥4, atrial runs, left atrium (LA) size >45 mm, left atrial appendage (LAA) flow ≤0.2 m/s, or spontaneous echo contrast in the LAA. The electrocardiographic and echocardiographic criteria were chosen as they have been repeatedly reported to predict AF; the same applies for four of the six items of the CHA2DS2-VASc score. The study end-point was the detection of one or more episodes of AF (≥2 min). RESULTS: Seventy-four patients underwent implantation of an ICM; one patient had AF at the date of implantation. After 6 months, AF was detected in 21/75 patients (28%), after 12 months in 25/75 patients (33.3%). 92% of AF episodes were asymptomatic. LA size >45 mm and the presence of atrial runs were independently associated with AF detection [hazard ratio 3.6 (95% confidence interval 1.6-8.4), P = 0.002, and 2.7 (1.2-6.7), P = 0.023, respectively]. CONCLUSIONS: The detection rate of AF is one-third after 1 year if candidates for an ICM after cryptogenic IS/TIA are selected by AF risk factors. LA dilation and atrial runs independently predict AF.

Efficacy and safety of zero-fluoroscopy ablation for supraventricular tachycardias. Use of optional contact force measurement for zero-fluoroscopy ablation in a clinical routine setting.

BACKGROUND: Conventional catheter ablation of cardiac arrhythmias is associated with radiation risks for patients and laboratory personnel. Widespread use of zero-fluoroscopic catheter ablation in clinical routine is limited by safety concerns. This study investigated the feasibility of zero-fluoroscopy catheter ablation using a three-dimensional mapping system and optional catheter contact force technology for an all-comers collective. PATIENTS AND METHODS: The study comprised 184 patients; 91 patients, including 29 pediatric patients, underwent a zero-fluoroscopic electrophysiology (EP) study using the EnSite NavX system with real-time visualization of all electrodes. These patients were matched to a control group, which was treated using fluoroscopy in the same period. Inclusion criteria were documented supraventricular tachycardia or a history of symptomatic paroxysmal supraventricular tachycardia. Transseptal access, if necessary, was achieved under transesophageal echocardiographic guidance for ablation of left-sided arrhythmias. Radiofrequency (using optional contact force measurement) or a cryotechnique was used for ablation. RESULTS: We observed no major acute complications. There were no significant differences between the two groups in the follow-up period. CONCLUSION: Zero-fluoroscopic catheter ablation is generally feasible in right-sided cardiac arrhythmias. Safety concerns regarding left atrial substrates or children can be overcome with optional real-time contact force measurement.

[Drug-induced long QT syndrome. Relevancy in intensive care medicine]. / Das medikamentös induzierte Long-QT-Syndrom. Bedeutung in der Intensivmedizin.

QT-prolonging drugs delay ventricular repolarization and, thus, favor the occurrence of Torsade de pointes (TdP). Intensive care patients are particularly endangered to suffer from this clinical picture as they often simultaneously exhibit multiple risk factors. In the following article, the most important risk factors for drug-induced long QT syndrome are described. An overview on how the QT interval can be influenced by various endo- and exogenous factors is provided. In addition, the measurement of this interval and potential sources of errors are described. Electrophysiological characteristics of TdP are delineated as well as important pathophysiological mechanisms of arrhythmogenesis, e.g., transmural dispersion of repolarization; T(peak)-T(end) interval as a marker for that dispersion is described. Potential explanations why prolongation of the QT interval is not the main or only factor for the proarrhythmic potential of QT-prolonging drugs are discussed. Furthermore, a summary of QT-prolonging drugs relevant in intensive care units is given and prevention of drug-induced long QT syndrome with consecutive TdP is discussed. Finally, recommendations for treatment of drug-induced TdP are reviewed.

[Catheter ablation of paroxysmal atrial fibrillation: extended recommendations considering safety improvements of pulmonary vein isolation with a cryoballoon--Case 11/2011]. / Katheterablation von paroxysmalem Vorhofflimmern: großzügigere Indikationsstellung durch verbesserte Sicherheit der Pulmonalvenenisolation mittels Cryoballon - Fall 11/2011.

HISTORY AND ADMISSION FINDINGS: A 71-year-old, male patient was referred to our clinic for paroxysmal palpitations with dyspnoe and fatigue since four years despite pharmacological treatment with flecainide and bisoprolol. INVESTIGATIONS: A paroxysmal atrial fibrillation was documented in a 24-hour Holter recording. A bicycle ergometry showed a hypertensive reaction during exercise without any sign of coronary insufficiency. Intracardiac thrombi could by excluded by transesophageal echocardiography. DIAGNOSIS, TREATMENT AND COURSE: The diagnosos of a drug-refractory paroxysmal atrial fibrillation was made and cryoballoon pulmonary vein isolation was performed. A follow-up 3 months after the ablation disclosed a freedom from atrial fibrillation documented in 7-day Holter recording. CONCLUSIONS: Compared to pharmacological rhythm control, interventional treatment has been established as more effective therapy for paroxysmal atrial fibrillation. However, patients should be referred to the ablation early enough to avoid structural atrial remodeling and thus transition into persistent or permanent atrial fibrillation. New technical developments e.g. cryoballoon catheter-system simplifies the procedure and has been reported to be effective and safe to use for circumferential pulmonary vein isolation. Should the very promising preclinical data on efficacy and safety of cryothermal energy ablation be confirmed by results of ongoing, controlled trials, the catheter ablation may become the fist-line treatment for all patients with paroxysmal atrial fibrillation.

Successful bridge to recovery using a microaxial blood pump in a patient with electrical storm and cardiogenic shock.

A 59-year-old patient with dilated cardiomyopathy and incessant ventricular tachycardia leading to progressive cardiogenic shock is presented. Due to hemodynamic instability, high dose catecholamines were required in addition to the implantation of an intraaortic balloon pump (IABP), which, however, appeared to further augment the frequency and duration of ventricular tachycardias. The implantation of a microaxial blood pump allowed catecholamine administration to be terminated, thereby, ending this vicious circle of catecholamine-driven electrical storm. Within 5 days, the patient was hemodynamically stabilized and kidney and liver function recovered with the support of intensive antiarrhythmic therapy (amiodarone, mexiletine, sotalol). During a 24-month follow-up, the patient had no further ICD shocks and no rehospitalization was required for treatment of congestive heart failure.

[Contact force control - the key to safe zero-fluoroscopy catheter ablation of atrioventricular nodal reentrant tachycardia]. / Die Anpresskraftkontrolle als Schlüssel zur sicheren strahlenfreien Katheterablation der AV-Knoten-Reentrytachykardie.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is a frequent supraventricular tachycardia in children and young adults. Despite favourable success rates of catheter ablation, conventional fluoroscopic catheter guidance is associated with risks of low-dose ionizing radiation for the patient and the personnel. Here we describe a technique for zero-fluoroscopy catheter ablation using contact force technology. PATIENTS AND METHODS: Zero-fluoroscopy catheter ablation was attempted in 12 patients with AVNRT (median age 20 years; range 11-75 years). An ablation catheter with integrated contact force sensor and a nonfluoroscopic electroanatomical mapping system was used for visualization of cardiovascular structures. Mean contact forces during mapping and ablation were restricted to an upper limit of 50 g to avoid cardiovascular injuries. RESULTS: Zero-fluoroscopy catheter ablation was performed successfully and uneventfully in all patients. There were no arrhythmia recurrences during a median follow-up of 6.2 months (range 2.7-12.8). CONCLUSION: Zero-fluoroscopy catheter ablation of AVNRT is possible and appears simple yet safe, when a nonfluoroscopic electroanatomical mapping system is used in combination with an ablation catheter with integrated contact force sensor. The presented technique could thus be easily employed in most electrophysiological laboratories.

[Risk stratification in non ischemic cardiomyopathy: a case report--Case 5/2010]. / Risikostratifizierung bei nichtischämischer Kardiomyopathie: Eine Kasuistik - Fall 5/2010.

HISTORY AND ADMISSION FINDINGS: A 65-year-old male patient with rapid increasing shortness of breath and newly diagnosed atrial fibrillation was admitted to our hospital. INVESTIGATIONS: The ECG revealed atrial fibrillation. Echocardiography showed severe decreased left ventricular function. The magnetic resonance imaging (MRI) scan confirmed the severe reduced left ventricular function with a two graded mitral regurgitation as well as a pronounced late enhancement in the posterobasal area of the interventricular septum. Cardiac catheterisation showed mild diffuse atherosclerosis of the coronary arteries without stenotic lesions. Multiple myocardial biopsies of the right ventricle revealed extensive remodelling processes with focal fibrosis in presence of mononuclear cell infiltrates, T-wave alternans and the heart rate variability were positive. DIAGNOSIS, TREATMENT AND COURSE: Nonischaemic cardiomyopathy (NICM) with severe reduced left ventriucular function was diagnosed. After successful electrical cardioversion and initiation of a sufficient heart failure treatment, the clinical symptoms as well as left ventricular function improved significantly. CONCLUSION: Risk stratification of sudden cardiac death remains a clinical challenge especially in NICM. Significantly predictors in ischaemic cardiomyopathy, such as heart rate turbulance (HRT) and T-wave alternans, are not useful or have no importance in NICM. However, the prognosis does not correlate with restricted left ventricular function in NICM. Cardiac MRI or marker of autonomic dysfunction could be helpful in risk stratification. How far late enhancement is a surrogate parameter or the real substrate for life threatening arrhythmias is still unclear. Non-invasive risk stratification could be helpful in borderline decisions, however, it should not be taken mandatory. Close-meshed control intervals of the clinical status under optimal medication are recommended, followed by a implantation of an implantable cardioverter-defibrillator (ICD) if needed. ICD implantation is superior to medical treatment in persistent depressed left ventricular function. The ideal time for ICD implantation in newly diagnosed NICM remains unclear at the moment.

[Atrial fibrillation - Links between principles of pathophysiology and treatment]. / Vorhofflimmern - Zusammenhänge pathophysiologischer und therapeutischer Prinzipien.

Atrial fibrillation is the most common supraventricular arrhythmia in humans, basic and clinical sciences are still developing. This present review aims to inform non-cardiologists respectively non-electrophysiologists about the most important pathophysiological concepts and their influence on therapeutical principles of atrial fibrillation. Moe's and Allessie's "multiple wavelet" theory is introduced as well as Haissaguerre's concept of ectopic triggering of paroxysmal atrial fibrillation and the most important aspects of atrial remodeling ("atrial fibrillation begets atrial fibrillation" according to Wijffels) during persistence of atrial fibrillation. Impact of these pathophysiological concepts is discussed within the context of medicamentous, surgical and interventional therapy. Concomitantly, limitations of these therapies due to pathophysiological considerations are delineated.

[Electrical cardioversion for atrial fibrillation]. / Die elektrische Kardioversion bei Vorhofflimmern.

Electrical cardioversion ist often the treatment of first choice for restoring sinus rhythm in patients with atrial fibrillation. This article reviews the management of patients undergoing electrical cardioversion. As risk of formation of an intra-atrial thrombus formation is low after a short duration of AF (less than 48 h), immediate cardioversion can be performed in these patients (except those with a high risk for thrombembolic events). However, if the AF has lasted for more than 48 hours, patients have to be treated either with anticoagulants for at least three weeks or an atrial thrombus has to be excluded by transesophageal echocardiography. Both options achieve the same short- or long-term success rate for cardioversion. Cardioversion is probably safe even if there are spontaneous echocardiographic contrasts as signs of potential thrombogenic slowing of atrial blood flow, but individual factors of risk/indication have to taken into account. Success rate of cardioversion depends on various patient characteristics as well as on some technical variables, biphasic instead of monophasic shocks being more effective. If there is an early recurrence of AF after initially successful cardioversion, administration of amiodarone (for 4 weeks) increases the success rate of subsequent cardioversion. After successful cardioversion subsequent antiarrhythmic therapy can reduce recurrence of AF. Thrombembolic complications are more frequent within the first few days after cardioversion. Indication for and duration of post-cardioversion anticoagulation depends on individual characteristics (CHADS(2) score) as well as on the duration of the preceding episode of AF.

[Inactivation of the intracardial cardioverter/defibrillator (ICD) antitachycardial function in dilated cardiomyopathy. Driver can again work in her occupation]. / Ausschalten der antitachykarden ICD-Funktion bei dilatativer Kardiomyopathie. Kraftfahrerin kann Beruf wieder ausüben.

HISTORY: Cardiac synchronization treatment with implanted cardiac defibrillator (CRT-ICD) had been given to a 52-year old women because she had markedly reduced left ventricular function and a left bundle branch block. She had already improved to NYHA class II two weeks after the initial diagnosis and treatment of a non-ischemic dilated cardiomyopathy at another hospital. A lorry drinving license was denied to her, a professional lorry driver. TREATMENT AND COURSE: By the time that the patient asked for a second opinion at our hospital six months later, left ventricular function had improved as a result of CRT and cardiac medication. There was thus no longer an indication for primary preventive ICD implantation, left ventricular function no longer being present. As the rhythmogenic hazard was comparable to that without implanted device (in which case professional driving would be allowed), anti-tachycardic ICD function was inactivated so that the patient could work again as a lorry driver. CONCLUSION: This case underlines the impact of the significance of the interval between diagnosis of a cardiac disease and primary preventive insertion of an ICD, as suggested by the guidelines, especially in patients with non-ischemic dilated cardiomyopathy.

Transient outward potassium current in rabbit atrium is depressed after short-time rapid atrial pacing but recovers after a longer pacing period.

In rabbit, after short-time rapid atrial pacing (RAP), atrial ion currents are reduced similarly as in human chronic atrial fibrillation (AF). Using the rabbit model, time-course of transient outward potassium current (I(to)) remodeling due to RAP was studied. RAP (600 bpm) was applied via an atrial lead for 0 (control), 24 and 120 h, n = 4 animals/group. Using patch clamp technique in whole-cell mode, current densities and biophysical properties were measured in isolated atrial myocytes. After 24 h of RAP, a reduction of peak I(to) (mean +/- SEM, test potential +50 mV, +37 degrees C) was observed (60.3 +/- 5.4 pA/pF (control, n = 20) vs. 28.0 +/- 2.5 pA/pF (24 h, n = 21)). Inactivation of I(to) was slower after 24 h, other biophysical properties were unaltered. However, I(to) recovered after 120 h: 51.7 +/- 4.5 pA/pF (n = 26, p = n.s. vs. control). Inactivation tended to also recover to initial values but was still different to control. Early I(to) remodeling due to RAP in rabbits seems to be more complex than previously thought: a time course of I(to) remodeling with swayings has to be considered when using the rabbit model of RAP in order to study early remodeling or rather its therapeutic manipulation.

[Cardiac resynchronization therapy in non-ischemic cardiomyopathy]. / Resynchronisationstherapie bei nicht-ischämischer Kardiomyopathie.

Cardiac resynchronization therapy is recommended in patients with advanced heart failure (usually NYHA class III or IV) despite optimal pharmacologic therapy, severe systolic dysfunction (eg, left ventricular ejection fraction < 35 percent) and intraventricular conduction delay or echocardiographic indices of dyssynchrony and wide QRS complex (eg, QRS > or = 120 ms). Viral infection is the most common cause of myocarditis and has been implicated in the development of non-ischemic cardiomyopathy. We report on a patient who developed progressive congestive heart failure caused by non-ischemic cardiomyopathy after liver transplantation and reactivation of the underlying hepatitis C. Due to an insufficient response to optimized pharmacological therapy, the patient was successfully treated using cardiac resynchronization therapy.

Circumferential mapping and electric isolation of pulmonary veins in patients with atrial fibrillation.

Information about the clinical efficacy and complications of the circumferential mapping and isolation of the pulmonary veins (PVs) in patients with atrial fibrillation (AF) is still limited. The present study included 75 patients (mean age 58 +/- 11 years, 20 women) with paroxysmal (n = 69) or persistent AF (n = 6). Mapping of PVs was performed with a circumferential mapping catheter. After preferential PV-left atrium (LA) electric inputs were defined, radiofrequency ablation was performed until complete isolation of the PVs from the LA was achieved. A total of 226 PVs were mapped; 195 (86%) showed typical PV potentials. Complete isolation of PVs from the LA was achieved in 173 PVs (89%). Detailed follow-up, including 7-day Holter monitoring at 1, 4, 9, and 12 months after intervention was performed. If AF reoccurred, PVs were mapped and reisolated. After a mean follow-up period of 230 +/- 133 days, 38 of 75 patients (51%) were in sinus rhythm. At 1, 4, and 9 months of follow-up, 31 of 65 patients (48%), 36 of 53 patients (68%, p = 0.04 as compared with the first month), and 21 of 28 patients (75%, p = 0.025 as compared with the first month), respectively, were in sinus rhythm. During follow-up, 30 patients (40%) underwent a second ablation procedure due to recurrence. Recurrences were related to resumption of PV muscle-left atrial conduction (27 patients) and/or extra PV foci (12 patients) or nonablated PVs (8 patients). Complications occurred in 17 patients (22%). PV stenosis was detected in 13 patients (25% to 50% in 7 patients and >50% in 6 patients). Pericardial effusion occurred in 4 patients. It was concluded that isolation of the PV from the LA is moderately effective in the prevention of AF recurrence and could be associated with serious acute and long-term complications.

Electrophysiologic characteristics of the spontaneous onset and termination of atrial fibrillation.

Electrophysiologic characterization of the onset and termination of atrial fibrillation (AF) is poorly defined. Our study population consisted of 21 consecutive patients (mean age 58 +/- 9 years, 6 women) with intermittent (10 patients) or persistent (11 patients) AF. Mapping of the left atrium (LA) and the right atrium (RA) during initiation and termination of AF was performed with a 64-electrode basket catheter. A total of 92 spontaneous AF onsets (in 16 patients) and 63 spontaneous AF terminations were analyzed. Irrespective of the origin of the triggering atrial premature complex (APC), the onset of AF was preceded by an intermediary rhythm that consisted of repetitive firing from the focus that generated the initial APC, reentry around the mitral annulus, or typical atrial flutter. The earliest fibrillatory activity was constantly produced by circumvented regions (generators) localized most frequently in the posterior wall of the LA. Generators of fibrillatory activity were not observed in the RA for any of the patients. In the RA, AF is maintained by a mixture of macro-reentry and driving wave fronts of left atrial origin. Four modes of AF termination were observed: a multifocal rhythm (19 episodes, 30%), left atrial tachycardia (17 episodes, 27%), direct conversion to sinus rhythm (15 episodes, 24%), and conversion to typical atrial flutter (12 episodes, 19%). A repetitive rapid rhythm initiated most often by APCs plays a crucial role in the initiation of AF via activation of the generators of fibrillatory activity. The LA plays a central role in the initiation of AF by serving as a substrate for generators of fibrillatory activity. Termination of AF consists of a heterogenous group of unstable rhythms.

Dissimilar atrial rhythms: coexistence of reentrant atrial tachycardia, atrioventricular nodal reentrant tachycardia and interatrial conduction block.

We report a patient in whom mapping of the right atrium with multipolar catheters and electroanatomic mapping revealed the presence of three dissimilar rhythms: a reentrant atrial tachycardia in the antero-lateral wall of the right atrium and an atrioventricular nodal reentrant tachycardia (AVNRT) isolated from each other and a conduction disturbance at the interatrial septum resulting in a rate-related interatrial block and a slow left atrial rhythm. The AVNRT was stopped with intravenous adenosine (6 mg) and induced repeatedly by atrial extrastimuli associated with a critical atrioventricular delay and dual atrioventricular nodal pathways. Electroanatomic mapping disclosed extensive fibrosis isolating viable myocardium of the antero-lateral wall from the rest of the right atrium. The viable myocardium in the antero-lateral wall was activated by a reentrant rhythm circulating around an islet of fibrosis located in the middle of the viable tissue. The AVNRT was ablated by a standard approach and the reentrant atrial tachycardia by producing a linear lesion bridging the central islet of fibrosis with the anterior tricuspid annulus. This case highlights the complicated nature of some dissimilar atrial rhythms and the power of electroanatomic mapping tools to reveal the exact mechanism and guide radiofrequency ablation.

Electrophysiologic characteristics of paroxysmal and chronic atrial fibrillation in human right atrium.

OBJECTIVES: The aim of the study was to analyze the electrophysiologic characteristics of paroxysmal (PAF) and chronic (CAF) atrial fibrillation (AF) in the human right atrium (RA). BACKGROUND: Differences that exist between PAF and CAF and the mechanisms of self-sustenance of these arrhythmias are incompletely understood. METHODS: A total of 53 patients with PAF (25 patients, mean age 59 +/- 6.1 years, 3 women) and CAF (28 patients, mean age 59 +/- 13 years, 7 women) underwent multisite mapping of the RA during ongoing AF using a 64-electrode basket catheter. Quantitative evaluation and three-dimensional activation patterns were performed using a computerized system. RESULTS: Patients with PAF, as compared with patients with CAF, had significantly longer AF cycle length, shorter time intervals with type III AF throughout the RA and a smaller number of endocardial breakthroughs (mean 51 +/- 19 vs. 104 +/- 40, p < 0.001). The majority of endocardial breakthrough points (88% in PAF patients and 98% in CAF patients) were located in the septal region and coincided anatomically with major interatrial connection routes. Coexistence of re-entrant and apparently focal activation determined maintenance of AF in the RA in PAF, whereas random re-entry was documented more frequently in patients with CAF. In patients with CAF, the duration of arrhythmia (in years) correlated strongly with the percentage of time during which type III AF was observed in the lateral wall of the RA (r = 0.71). CONCLUSIONS: Clinical PAF and CAF, as recorded in the RA, have, at least quantitatively, distinct electrophysiologic features and different mechanisms of maintenance.

Maintenance of sinus rhythm after electrical cardioversion of persistent atrial fibrillation; sotalol vs bisoprolol.

AIMS: The purpose of the study was to compare the efficacy and safety of sotalol and bisoprolol in the maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation. METHODS: Patients (n=128) were randomized to sotalol (80 mg b.i.d.) or bisoprolol (5 mg x day(-1)). Patients with contraindications to beta-blockers, class III antiarrhythmic drugs or prior treatment with use of study medication for prevention of atrial fibrillation were excluded. Follow-up clinical evaluation was performed 1 day and 1 month after cardioversion and thereafter at 3-month intervals. RESULTS: There were no group differences in baseline clinical characteristics. After a follow-up of 12 months, 59% of all patients were still in sinus rhythm. The fraction remaining in sinus rhythm was calculated for the two groups by Kaplan--Meier analysis. During follow-up, 41% of patients on sotalol and 42% on bisoprolol developed atrial fibrillation (ns). In two patients (3.1%) on sotalol, life-threatening proarrhythmias (torsade de pointes tachycardias) occurred, whereas none were found in the bisoprolol group. Symptomatic bradycardias occurred in two patients on sotalol and three on bisoprolol. CONCLUSION: This study demonstrates that sotalol (160 mg x day(-1)) and bisoprolol (5 mg x day(-1)) are equally effective in maintaining sinus rhythm. Because of the side effects of sotalol, bisoprolol seems to be advantageous for maintenance of sinus rhythm after cardioversion of atrial fibrillation.

Inappropriate shock delivery due to ventricular double detection with a biventricular pacing implantable cardioverter defibrillator.

This report describes a patient with advanced heart failure, pronounced intraventricular conduction delay, and ventricular tachycardias who underwent implantation of a multisite pacing ICD. Pacing leads were placed in the right atrium, right ventricular apex, and to the left ventricular posterior wall via a coronary sinus vein. The system proved to have correct sensing and pacing function in an atrial synchronized biventricular pacing mode and an appropriate detection of ventricular fibrillation. However, 1 month after implantation the patient received an inappropriate shock delivery due to double detection of ventricular premature beats. The inherent detection problem of dual ventricular sensing is discussed.